In previous studies, thyroid hormone was observed to determine which of two types of cardiac myosin differing in adenosinetriphosphatase activity and physicochemical characteristics was synthesized. Other hormonal and nutritional influences on the molecular characteristics of myosin will be examined. Human cardiac myosin will be characterized, and the influence of cardiac pathology and of hormonal and nutritional abnormalities will be studied. Studies will be continued on the serum growth factors that influence replication of vascular cells with the aim of purification of active factors and determination of their tissue specificity. BIBLIOGRAPHIC REFERENCES: Lanzillo, J.J. and B.L. Fanburg. The estimation and comparison of molecular weight of angiotensin 1 converting enzyme by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Biochim. Biophys. Acta 439: 125, 1976. Yazaki, Y. and M.S. Raben. Comparison of the synthesis of the light and heavy chains of cardiac myosin. Proc. 8th International Study Group for Research in Cardiac Metabolism, Tokyo, Japan, 1976. (in press).